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IArc Interface
IArc Interface
- GetCurvature
- SetCurvature
- Init
- IsValid
- MakeValid
- SetEndPoint
The interface is implemented by arcs and 2D straight lines.
To access 2D end points of the arc query ILine2D from
this interface. Use
IArcEx queried from this to perform additional
calculations related to arc.
IArc interface is returned from other interfaces which give access to more
complex objects. To create a standalone arc to for some calculations call
IDIObjGenerator.Create or
IDIObjGenerator.Create2 with
eType parameter set to eObjTypeArc member of
EObjectType
enumeration. The returned IUnknown reference
has actual type IArc. Use query if your environment does not allow direct cast.
See also Pipes sample,
Interface List
HRESULT GetCurvature(double* curv)
Parameters
curv - [out] The returned
Curvature of the arc
- Remarks:
The method returns Curvature of the
arc
HRESULT SetCurvature(double curv)
Parameters
curv - [in] New value for
Curvature of the arc
- Remarks:
The method does no check validity of
the resulting arc, assuming that further modifications may follow before usage
of the arc object. If arc has been modified with this method the Init method
below must be called prior calling enhanced methods ( any method of
IArcEx, except of IArcEx.Radius() )
HRESULT Init(VARIANT_BOOL *success)
Parameters
success - [out, retval] The
returned success code. True if the arc was
valid or false otherwise.
- Remarks:
This method updates internal state of the software object. It must be called
after any changes to primary properties of the arc (ends and curvature) and
before calling enhanced methods exposed by the arc (any method of
IArcEx, except of IArcEx.Radius() ). False return code
means that the arc is in invalid state and cannot be initialized. To resolve
this issue either set curvature to a number in [-d/2, d/2] range, where d is
distance between arc ends or reduce distance between ends to 2/Curvature and
call the method again. Note that arcs with curvature 0 (straight lines) are
always valid.
Note once this method was called successfully (arc is valid) the arc becomes
Initialized. Calling this method again for a
initialized arc is not an error and does not affect performance.
HRESULT IsValid(VARIANT_BOOL *success*valid))
Parameters
success - [out, retval] True if
the arc is
valid or false otherwise.
- Remarks:
HRESULT MakeValid(VARIANT_BOOL *modified)
Parameters
modified - [out,retval] True if curvature was modified
and the arc has become valid. False if there were no changes because the arc was
valid prior the call
- Remarks:
The method exits without any changes and returns false if the arc was valid
otherwise it modifies curvature of the arc to the nearest valid value and
returns true. See Init() for more information.
HRESULT SetEndPoint(int end, double x, double y)
Parameterss
end - [in] 0 for the first end 1 for the second end. No
other values are accepted
x, y - [in] New coordinates of the end point
- Remarks:
This method modifies the specified end of the arc. As curvature remains unchanges
the arc may become invalid. See Init() above for more information.
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